For information on the synchronizing lights module, see the Systems Operation, "Synchronizing Lights Module".
The reverse power relay (RPR) provides system protection when the generator set is in parallel with other units. If the engine loses power, then the other parallel unit attempts to motorize the engine and the generator. If the voltage is present at the generator leads connection, then the voltage regulator maintains the field excitation. The engine and the generator remain magnetically coupled. The generator then drives the engine. Power no longer flows OUT of the generator. Power flows INTO the failing generator. This reverse flow of power could possibly result in overloading of the other generators and the whole system.
The reverse power relay (RPR) is a single phase relay which is energized by power in one direction. The power flows into the generator instead of out of the generator. In a reverse power fault, the relay (RPR) closes the contact across the RPR (5 and 6) (line 19) that is located on the DC Schematic. The GSC records an SP1 fault and the engine is shutdown. If the generator output circuit breaker is equipped with a shunt trip, then the generator is taken off the line. See Testing And Adjusting, "Schematics And Wiring Diagrams".
After the reverse power fault is corrected, the generator set control (GSC) is reset by turning the engine control switch (ECS) to the OFF/RESET position. If the generator set is equipped with a shunt trip, then reset the generator output circuit breaker.
The operation of the RPR is tested by pushing the test button on the RPR while the generator is on load. Depress the test button for 10 to 15 seconds.
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To avoid personal injury from electrical shock, do NOT touch the high voltage terminal while adjusting the reverse power relay. |
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The trip point of the relay is adjustable in the field. The relay trip point is normally set at the factory at approximately 15% of the generator rated kW.